LT5570IDD-PBF_技术文档

LT5570

Fast Responding, 40MHz

to 2.7GHz Mean-Squared

Power Detector

FEATURES

DESCRIPTION

TheLT^®5570isa40MHzto2.7GHzmonolithicLogarithmic

Mean-Squared RF power detector. It is capable of RMS

measurement of an AC signal with wide dynamic range,

from –52dBm to 13dBm depending on frequency. The

power of the AC signal in an equivalent decibel-scaled

value is precisely converted into DC voltage on a linear

scale,independentofthecrestfactorofthewaveforms.The

LT5570issuitableforprecisionRFpowermeasurementand

level control for a wide variety of RF standards, including

CDMA, W-CDMA, CDMA2000, TD-SCDMA and WiMAX.

The DC output is buffered with a low output impedance

ampliﬁer capable of driving a high capacitance load.

n

Frequency Range: 40MHz to 2.7GHz

n

Accurate RMS Power Measurement of High Crest

Factor Modulated Waveforms

n

Linear DC Output vs Input Power in dBm

n

Linear Dynamic Range: Up to 60dB

n

Exceptional Accuracy over Temperature: 0.ꢀdB

n

Fast Response Time: 0.5μs Rise Time,

8μs Fall Time

Low Supply Current: 26.5mA

n

Low Impedance Output Buffer Capable of Driving

High Capacitance Load

n

Small 3mm × 3mm 10-Lead DFN Package

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

Protected by U.S. Patents including 7262661, 7259620, 7268608.

APPLICATIONS

n

RMS Power Measurement

n

RF Power Control

n

Receive and Transmit Gain Control

W-CDMA, CDMA2000, TD-SCDMA, WiMAX

n

RF Instrumentation

TYPICAL APPLICATION

40MHz to 2.7GHz Mean-Squared Power Detector

Output Voltage, Linearity Error vs Input Power, 25°C (2140 MHz)

2.4

2.0

1.6

1.2

3

2

1

0

5V

22nF

1MF

1nF

1

2

10

9

RF

INPUT

V

FLTR

EN

CC

1:4

+

ENABLE

IN

3

4

8

7

NC

DEC

LT5570

DNC

–

IN

0.8

0.4

0

–1

–2

–3

5

6

GND

OUT

V

OUT

CW

4CH WCDMA

3CH CDMA2000

5570 TA01a

–15

RF INPUT POWER (dBm)

5

15

–45

–35

–25

–5

5570 TA01b

5570f

1

LT5570

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Note 1)

TOP VIEW

Supply Voltage.........................................................5.5V

Enable Voltage .................................–0.3V to V + 0.3V

V

1

2

3

4

5

10 FLTR

CC

+

CC

IN

9

8

7

6

EN

Input Signal Power (Differential)..........................15dBm

DEC

DNC

OUT

T

JMAX

.................................................................... 125°C

–

IN

Operating Temperature Range.................. –40°C to 85°C

Storage Temperature Range................... –65°C to 125°C

GND

DD PACKAGE

10-LEAD (3mm s 3mm) PLASTIC DFN

CAUTION:Thispartissensitivetoelectrostaticdischarge.It

isveryimportantthatproperESDprecautionsbeobserved

when handling the LT5570.

T

= 125°C, θ = 43°C/W

JA

JMAX

EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

TAPE AND REEL

PART MARKING

PACKAGE DESCRIPTION

10-Lead (3mm × 3mm) Plastic DFN

TEMPERATURE RANGE

–40°C to 85°C

LT5570IDD#PBF

LT5570IDD#TRPBF

LCJQ

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges.

Consult LTC Marketing for information on non-standard lead based ﬁnish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel speciﬁcations, go to: http://www.linear.com/tapeandreel/

The l denotes the speciﬁcations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise speciﬁcations are at T_A= 25°C, V_CC= 5V, EN = 5V, unless otherwise noted. Test circuits are shown in

Figures 1 and ꢀ. (Notes 2 and ꢀ).

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

AC Input

l

Input Frequency Range (Note 4)

Input Impedance

40 to 2700

200/1

MHz

Ω/pF

f

RF

= 500MHz

RF Input Power Range

Linear Dynamic Range (Note 5)

Output Slope

CW Input; 1:4 Balun Matched into 50Ω Source

–52 to 13

62

dBm

dB

1dB Linearity Error, T = –40°C to 85°C

A

36.9

mV/dB

dBm

dB

Logarithmic Intercept

–54.8

0.5

Output Variation vs Temperature

Normalized to Output at 25°C

–40°C < T < 85°C; P = –50dBm to 13dBm

A

IN

Deviation from CW Response

11dB Peak to Average Ratio (3-Carrier CDMA2K)

12dB Peak to Average Ratio (4-Carrier WCDMA)

0.4

0.3

dB

nd

2

3

Order Harmonic Distortion

At RF Input; CW Input; P = 10dBm

61

66

dBc

IN

rd

At RF Input; CW Input; P = 10dBm

IN

5570f

2

LT5570

The l denotes the speciﬁcations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise speciﬁcations are at T_A= 25°C, V_CC= 5V, EN = 5V, unless otherwise noted. Test circuits are shown in

Figures 1 and ꢀ. (Notes 2 and ꢀ).

PARAMETER

= 880MHz

CONDITIONS

MIN

TYP

MAX

UNITS

f

RF

RF Input Power Range

Linear Dynamic Range (Note 5)

Output Slope

CW Input; 1:4 Balun Matched into 50Ω Source

–48 to 13

61

dBm

dB

1dB Linearity Error, T = –40°C to 85°C

A

37.7

mV/dB

dBm

dB

Logarithmic Intercept

–51.9

0.4

Output Variation vs Temperature

Normalized to Output at 25°C

–40°C < T < 85°C; P = –47dBm to 13dBm

A

IN

Deviation from CW Response

11dB Peak to Average Ratio (3-Carrier CDMA2K)

12dB Peak to Average Ratio (4-Carrier WCDMA)

0.3

0.2

dB

nd

2

3

Order Harmonic Distortion

= 2140MHz

At RF Input; CW Input; P = 10dBm

60

61

dBc

IN

rd

At RF Input; CW Input; P = 10dBm

IN

f

RF

RF Input Power Range

Linear Dynamic Range (Note 5)

Output Slope

CW Input; 1:4 Balun Matched into 50Ω Source

–38 to 13

51

dBm

dB

1dB Linearity Error, T = –40°C to 85°C

47

A

34.8

–43.6

36.5

39.0

mV/dB

dBm

dB

Logarithmic Intercept

–40.6

0.3

–37.6

Output Variation vs Temperature

Normalized to Output at 25°C

–40°C < T < 85°C; P = –36dBm to 13dBm

A

IN

Deviation from CW Response

11dB Peak to Average Ratio (3-Carrier CDMA2K)

12dB Peak to Average Ratio (4-Carrier WCDMA)

0.1

0.2

dB

f

RF

= 2700MHz

RF Input Power Range

Linear Dynamic Range (Note 5)

Output Slope

CW Input; 1:4 Balun Matched into 50Ω Source

–35 to 13

48

dBm

dB

1dB Linearity Error, T = –40°C to 85°C

A

36.4

mV/dB

dBm

dB

Logarithmic Intercept

–38.5

0.2

Output Variation vs Temperature

Normalized to Output at 25°C

–40°C < T < 85°C; P = –31dBm to 13dBm

A

IN

Deviation from CW Response

11dB Peak to Average Ratio (3-Carrier CDMA2K)

12dB Peak to Average Ratio (4-Carrier WCDMA)

0.1

0.5

dB

Output

Output DC Voltage

Output Impedance

Sourcing/Sinking

Rise Time

No RF Signal Present

0.1

100

5/2.5

0.5

V

Ω

mA

μS

0.2V to 1.6V, 10% to 90%, C1 = 22nF, f = 2140MHz

RF

Fall Time

1.6V to 0.2V, 90% to 10%, C1 = 22nF, f = 2140MHz

8

RF

5570f

3

LT5570

The l denotes the speciﬁcations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise speciﬁcations are at T_A= 25°C, V_CC= 5V, EN = 5V, unless otherwise noted. Test circuits are shown in

Figures 1 and ꢀ. (Notes 2 and ꢀ).

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Enable (EN) Low = Off, High = On

EN Input High Voltage (On)

EN Input Low Voltage (Off)

Enable Pin Input Current

Turn ON Time

l

2

V

1

EN = 5V

68

1

μA

μs

V

OUT

V

OUT

within 10% of Final Value, C1 = 22nF

< 0.1V, C1 = 22nF

Turn OFF Time

5

Power Supply

l

Supply Voltage

4.75

5

5.25

32.5

100

V

mA

μA

Supply Current

26.5

0.1

Shutdown Current

EN = 0V, V = 5V

CC

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note ꢀ: A 1:4 input transformer is used for the input matching to 50Ω

source.

Note 4: Operation over a wider frequency range is possible with reduced

performance. Consult the factory for information and assistance.

Note 2: Speciﬁcations over the –40ºC to +85ºC temperature range are

assured by design, characterization and correlation with statistical process

controls.

Note 5: The linearity error is calculated by the difference between the

incremental slope of the output and the average output slope from

–30dBm to 2dBm. The dynamic range is deﬁned as the range over which

the linearity error is within 1dB.

5570f

4

LT5570

TYPICAL PERFORMANCE CHARACTERISTICS

(Test Circuits Shown in Figures 1 and ꢀ)

Output Voltage vs Frequency

Linearity Error vs Frequency

2.4

3

2

1

0

T

= 25°C

T = 25°C

A

2.0

1.6

1.2

0.8

0.4

0

–1

–2

–3

500MHz

880MHz

2140MHz

2700MHz

500MHz

880MHz

2140MHz

2700MHz

–15

RF INPUT POWER (dBm)

5

15

–15

RF INPUT POWER (dBm)

5

15

–55 –45 –35 –25

–5

–55 –45 –35 –25

–5

5570 G01

5570 G02

Output Voltage, Linearity Error vs

RF Input Power, 500MHz

Linearity Error vs RF Input Power,

500MHz Modulated Waveforms

3

2

1

0

2.4

2.0

1.6

1.2

3

2

1

0

T

= 25°C

A

–1

–2

–3

0.8

0.4

0

–1

–2

–3

CW

T

= –40°C

= 25°C

= 85°C

A

4CH WCDMA

3CH CDMA2000

–15

RF INPUT POWER (dBm)

5

15

–55 –45 –35 –25

–5

–15

RF INPUT POWER (dBm)

5

15

–55 –45 –35 –25

–5

5570 G04

5570 G03

Output Voltage, Linearity Error vs

RF Input Power, 880MHz

Linearity Error vs RF Input Power,

880MHz Modulated Waveforms

2.4

2.0

1.6

1.2

3

2

1

0

3

2

1

0

T

= 25°C

A

0.8

0.4

0

–1

–2

–3

–1

–2

–3

T

= –40°C

= 25°C

= 85°C

CW

A

4CH WCDMA

3CH CDMA2000

–15

RF INPUT POWER (dBm)

5

15

–55 –45 –35 –25

–5

–15

RF INPUT POWER (dBm)

5

15

–55 –45 –35 –25

–5

5570 G05

5570 G06

5570f

5

LT5570

TYPICAL PERFORMANCE CHARACTERISTICS ^{(Test Circuits Shown in Figures 1 and ꢀ)}

Output Voltage, Linearity Error vs

RF Input Power, 2140MHz

Linearity Error vs RF Input Power,

2140MHz Modulated Waveforms

3

2

1

0

2.4

2.0

1.6

1.2

3

2

1

0

T

= 25°C

A

–1

–2

–3

0.8

0.4

0

–1

–2

–3

CW

T

= –40°C

= 25°C

= 85°C

A

4CH WCDMA

3CH CDMA2000

–15

RF INPUT POWER (dBm)

5

15

–45

–35

–25

–5

–15

RF INPUT POWER (dBm)

5

15

–45

–35

–25

–5

5570 G08

5570 G07

Output Voltage, Linearity Error vs

RF Input Power, 2700MHz

Linearity Error vs RF Input Power,

2700MHz Modulated Waveforms

2.4

2.0

1.6

1.2

3

2

1

0

3

2

1

0

T

= 25°C

A

0.8

0.4

0

–1

–2

–3

–1

–2

–3

T

= –40°C

= 25°C

= 85°C

CW

A

4CH WCDMA

3CH CDMA2000

–15

RF INPUT POWER (dBm)

5

15

–45

–35

–25

–5

–15

RF INPUT POWER (dBm)

5

15

–45

–35

–25

–5

5570 G09

5570 G10

Logarithmic Intercept vs

Frequency

Slope vs Frequency

–35

–40

–45

–50

42

40

38

36

T

= 25°C

T

= 25°C

A

–55

–60

34

32

0

1000 1500 2000 2500 3000

FREQUENCY (MHz)

0

1000 1500 2000 2500 3000

FREQUENCY (MHz)

500

5570 G12

5570 G11

5570f

6

LT5570

(Test Circuits Shown in Figures 1 and ꢀ)

TYPICAL PERFORMANCE CHARACTERISTICS

Output Transient Response,

C1 = 22nF

Output Transient Response,

C1 = 1μF

3.0

2.5

6

2

3.0

2.5

6

2

RF

PULSE

OFF

RF

PULSE

OFF

RF

PULSE

OFF

RF

PULSE

OFF

RF PULSE ON

AT 2140MHz

2.0

1.5

–2

–6

2.0

1.5

–2

–6

P

= 10dBm

= 0dBm

P

= 10dBm

= 0dBm

IN

P

= –10dBm

= –20dBm

P

= –10dBm

= –20dBm

IN

1.0

0.5

0

–10

–14

–18

1.0

0.5

0

–10

–14

–18

P

IN

= –30dBm

IN

0

100 200 300 400 500 600 700 800 900 1000

TIME (μs)

0

5

10 15 20 25 30 35 40 45 50

TIME (μs)

5570 G14

5570 G13

Slope Distribution vs

Temperature

Logarithmic Intercept Distribution

vs Temperature

Supply Current vs Supply Voltage

40

35

45

40

35

30

25

20

15

10

5

45

40

35

30

25

20

15

10

5

TA = –40oC

TA = 25oC

TA = 85oC

TA = –40oC

TA = 25oC

TA = 85oC

30

25

20

15

10

T

= –40°C

= 25°C

= 85°C

A

0

4.50

4.75

5.00

5.25

5.50

35.4 36 36.6 37.2 37.8 38.4 39

SLOPE (mV/dB)

–44 –43 –42 –41

LOGARITHMIC INTERCEPT (dBm)

–40 –39 –38

SUPPLY VOLTAGE (V)

5570 G17

5570 G15

5570 G16

Input Return Loss vs Frequency

Reference in Figure ꢀ

Input Return Loss vs Frequency

Reference in Figure 1

Supply Current vs RF Input Power

29

28

27

26

0

T

= 25°C

A

–5

–10

–15

–10

–15

25

24

23

–20

–25

–30

–20

–25

–30

880MHz

2140MHz

2700MHz

–15

RF INPUT POWER (dBm)

5

15

–55 –45 –35 –25

–5

0

100 200 300 400 500 600 700 800 9001000

FREQUENCY (MHz)

500

1000

1500

FREQUENCY (MHz)

2000

2500

3000

5570 G18

5570 G19

5570 G20

5570f

7

LT5570

PIN FUNCTIONS

V

(Pin 1): Power Supply Pin for the Bias Circuits. Typi- OUT (Pin 6): DC Output Pin. The output impedance is

CC

cal current consumption is 26.5mA. This pin should be mainly determined by an internal 100Ω series resistance

externally bypassed with 1nF and 1μF chip capacitors.

that provides output circuit protection if the output is

shorted to ground.

–

+

IN , IN (Pins 2, 4): Differential Input Signal Pins. These

pins are preferably driven with a differential signal for DNC (Pins 7, 8): Do Not Connect. Don’t connect any

optimum performance. The pins are internally biased to external component at these pins. Avoid a long wire or

V

– 1.224V and should be DC blocked externally. The metal trace on the PCB.

CC

differential impedance is about 200Ω.

EN (Pin 9): Enable Pin. An applied voltage above 2V will

DEC (Pin ꢀ): Input Common Mode Decoupling Pin. This activate the bias for the IC. For an applied voltage below

pin is internally biased to V – 1.224V. The input imped- 1V, the circuits will be shut down (disabled) with a corre-

CC

ance is about 1.75KΩ in parallel with a 10pF internal sponding reduction in power supply current. If the enable

shunt capacitor to ground. The impedance between DEC function is not required, then this pin should be con-

+

–

and IN (or IN ) is about 100Ω. The pin can be connected nected to V . Typical enable pin input current is 68μA for

CC

to the center tap of an external balun. An ac-decoupling EN = 5V. Note that at no time should the Enable pin voltage

capacitor may be connected to ground to maintain the IC be allowed to exceed V by more than 0.3V.

CC

performance if necessary.

FLTR(Pin10):ConnectionforanExternalFilteringCapaci-

GND (Pin 5, Exposed Pad): Circuit Ground Return for tor C1. A minimum 22nF capacitor is required for stable

the Entire IC. This must be soldered to the printed circuit ac average power measurement. This capacitor should be

board ground plane.

connected between Pin 10 and V .

CC

5570f

8

LT5570

TEST CIRCUITS

5V

C3

1MF

C1

22nF

C2

1nF

1

2

10

9

RF

INPUT

V

FLTR

EN

T1

CC

L1

1:4

1

5

3

2

4

+

ENABLE

R1

100k

IN

3

4

8

7

C7

J1

LT5570

DNC

NC

DEC

–

IN

5

6

C4

1nF

OUT

GND

OUT

EXPOSED PAD

C6

(OPT)

5570 F01

REF DES

C2, C4

C1

VALUE

1nF

SIZE

PART NUMBER

AVX 0402ZC102KAT

AVX 0402YC223KAT

0402

0603

0402

22nF

1μF

C3

Taiyo Yuden LMK107BJ105MA

CRCW0402100KFKED

R1

100k

FREQUENCY

T1

L1

L1 P/N

C7

880MHz

2140MHz

2700MHz

MURATA LDB21869M20C-001

MURATA LDB212G1020-001

MURATA LDB212G4020-001

8.2nH

3.3nH

1.2nH

TOKO LL1005-FH8N25

TOKO LL1005-FH3N35

TOKO LL1005-FH1N25

2.7pF

0.5pF

1pF

MURATA GRM1555C1H2R7DZ01

MURATA GRM1555C1HR50CZ01

MURATA GRM1555C1H1R0DZ01

Figure 1. Test Schematic for 880MHz, 2140MHz and 2700MHz Applications

Figure 2. Top Side of Evaluation Board for 880MHz, 2140MHz and 2700MHz Applications

5570f

9

LT5570

TEST CIRCUITS

5V

C3

1MF

C1

22nF

C2

1nF

T2

1

2

10

9

RF

INPUT

C7

1nF

V

FLTR

EN

ETC4-1-2

CC

+

L1

0

1:4

4

5

3

2

1

ENABLE

IN

C8

OPT

R1

100k

3

4

8

7

J1

C9

0

LT5570

DNC

NC

DEC

–

IN

5

6

C4

1nF

GND

OUT

EXPOSED PAD

OUT

C6

(OPT)

5570 F03

REF DES

C2, C4, C7

C1

VALUE

1nF

SIZE

PART NUMBER

REF DES

R1

VALUE

100k

1:4

SIZE

PART NUMBER

0402

0603

AVX 0402ZCI02KAT

AVX 0402YC223KAT

0402

CRCW0402100KFKED

ETC4-1-2

22nF

1μF

T2

C3

Taiyo Yuden LMK107BJ105MA

C8

OPT

0

0402

C9, L1

CJ05-000M

Figure ꢀ. Test Schematic for 40MHz to 860MHz Applications

Figure 4. Top Side of Evaluation Board for 40MHz to 860MHz Applications

5570f

10

LT5570

APPLICATIONS INFORMATION

TheLT5570isamean-squaredRFpowerdetector, capable

of measuring an RF signal over the frequency range from

40MHz to 2.7GHz, independent of input waveforms with

different crest factors such as CW, CDMA, WCDMA, TD-

SCDMA and WiMAX signals. A wide dynamic range is

achievedwithverystableoutputwithinthefulltemperature

range from –40˚C to 85˚C.

The LT5570’s differential inputs are optimally driven from

a fully balanced source. When the signal is from a single-

ended 50Ω source, conversion to a differential signal is

required to achieve the maximum dynamic range. This

is best achieved using a 1:4 balun to match the internal

200Ω input impedance as shown in Figures 1 and 3. This

impedance transformation results in 6dB voltage gain. At

high frequency, additional LC elements may be needed

for input impedance matching due to the parasitics of the

transformer and PCB trace.

RF Inputs

The differential RF inputs are internally biased at

V

– 1.224V. The differential impedance is about 200Ω.

The approximate RF input power range of the LT5570 is

60dB at frequencies up to 900MHz, even with high crest

factor signals such as a 4-carrier W-CDMA waveform.

HowevertheminimumdetectableRFpowerleveldegrades

as the input RF frequency increases.

CC

These pins should be DC blocked when connected to

ground or other matching components. The impedance

vs. frequency of the differential RF input is detailed in the

following table.

Due to the high RF input impedance of the LT5570, a

narrow band L-C matching network can be used for the

conversion of a single-ended to balanced signal as well.

By this means, the sensitivity and overall linear dynamic

range of the detector remain the same, without using an

RF balun.

Table 1. RF Differential Input Impedance

S11

FREQUENCY DIFFERENTIAL INPUT

(MHz)

IMPEDANCE (Ω)

MAG

0.606

0.605

0.604

0.603

0.602

0.601

0.599

0.598

0.596

0.593

0.591

0.589

0.586

0.582

ANGLE (°)

–0.1

–0.3

–0.5

–1.1

–1.6

–2.1

–2.7

–3.2

–3.8

–4.4

–5.0

–5.6

–6.2

–6.9

–7.6

–8.4

–9.2

40

204 –j 0.6

204 –j 1.8

100

200

204 –j 3.6

The LT5570 can also be driven in a single-ended con-

ﬁguration. Figure 5 shows the simpliﬁed circuit of this

single-ended conﬁguration. The DEC Pin is preferably ac-

coupled to ground via a capacitor rather than left ﬂoating.

400

203.5 –j 7.3

202.8 –j 10.9

201.8 –j 14.5

200.6 –j17.9

199.1 –j21.3

197.3 –j24.7

195.4 –j27.9

193.2 –j31.1

190.8 –j34.2

188.2 –j37.4

185.3 –j40.4

181.9 –j43.5

178.3 –j46.4

174.4 –j49.3

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

2800

3000

LT5570

+

IN

1nF

1007

DEC

1nF

–

IN

RF

INPUT

1007

5570 F05

Figure 5. Single-Ended Input Conﬁguration

5570f

11

LT5570

APPLICATIONS INFORMATION

40

35

30

25

20

15

10

5

320

280

240

200

160

120

80

2.4

AT 2140MHZ, P = 10dBm

IN

2.0

1.6

1.2

0.8

500MHz

880MHz

0.4

RESIDUAL RIPPLE

RISE TIME

FALL TIME

40

2140MHz

2700MHz

0

0.0

–10

–50 –40 –30 –20

INPUT POWER (dBm)

0

10

0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

EXTERNAL FILTERING CAPACITOR C1 (μF)

5570 F07

5570 F06

Figure 6. Output Voltage and Linearity Error vs

RF Input Power in Single-ended Input Conﬁguration

Figure 7. Residual Ripple, Output Transient

Times vs. Filtering Capacitor C1

+

–

The DEC pin can be tied to the IN (or IN ) Pin directly

and ac-coupled to ground while the RF signal is applied

C1’s value has a dominant effect on the output transient

response. The lower the capacitance, the faster the output

rise and fall times as illustrated in Figure 7. For signals

withAMcontentsuchasW-CDMA, ripplecanbeobserved

when the loop bandwidth set by C1 is close to the modu-

lation bandwidth of the signal. A 4-carrier W-CDMA RF

signal is used as an example in this case. The trade-offs

of residual ripple vs. output transient time are also as

shown in Figure 7.

–

+

to the IN (or IN ) Pin. By simply terminating the signal

side of the inputs with a 100Ω resistor to ground in front

of the ac-blocking capacitor and coupling the other side

to ground using a 1nF capacitor, a broadband 50Ω input

match can be achieved with typical input return loss better

than 12dB from 40MHz to 2.7GHz.

Since there is no voltage conversion gain from imped-

ance transformation in this case, the sensitivity of the

detector is reduced by 6dB. The linear dynamic range is

reduced by the same amount correspondingly as shown

in Figure 6.

In general, the LT5570 output ripple remains relatively

constant regardless of the RF input power level for a ﬁxed

C1 and modulation format of the RF signal. Typically, C1

must be selected to average out the ripple to achieve the

desiredaccuracyofRFpowermeasurement.Foratwo-tone

RF signal with equal power applied to the LT5570 input,

Figure 8 shows the variation of the output dc voltage and

its RMS value of the residual ac voltage as a function of

the delta frequency. Both values are referred to dB by

normalizing them to the output slope (about 37mV/dB).

In this measurement, C1 = 22nF. Increasing C1 will shift

both curves toward a lower frequency.

External Filtering (FLTR) Capacitor C1

This pin is internally biased at V – 0.13V via a 2k resistor

CC

from voltage supply V . To assure stable operation of the

CC

LT5570, an external capacitor C1 with a value of 22nF or

higher is required to connect the FLTR Pin to V . Don’t

CC

connect this ﬁltering capacitor to ground or any other

low voltage reference at any time to avoid an abnormal

start-up condition.

5570f

12

LT5570

APPLICATIONS INFORMATION

8

7

6

5

4

3

2

1

0

1

C1 = 22nF

DC VOLTAGE VARIATION

LT5570

0

V

CC

50μA

–1

–2

–3

1007

OUT

R

SS

OUTPUT AC RIPPLE

INPUT

V

OUT

C

LOAD

0.1

AM MODULATION FREQUENCY (MHz)

0.01

1

10

3566 F09

5570 F08

Figure 8. Output DC Voltage Variation and

Residual Ripple vs AM Modulation Frequency

Figure 9. Simpliﬁed Circuit Schematic of the Output Interface

ThehighperformanceRFcircuitsinsidetheLT5570enable

it to handle output ripple as high as 2dB without losing its

powerdetectionaccuracy.Theripplecanbefurtherreduced

for optimal transient time with an additional RC lowpass

ﬁlter at the output as discussed in the next section.

175ns. When the output is resistively terminated or open,

the fastest output transient response is achieved when a

large signal is applied to the RF input port. The total rise

time of the LT5570 is about 0.5μs and the total fall time

is 8μs, respectively, for full-scale pulsed RF input power.

The speed of the output transient response is dictated

mainly by the ﬁltering capacitor C1 (at least 22nF) at the

FLTR pin. See the detailed output transient response in

theTypicalPerformanceCharacteristicssection.Whenthe

RF input has AM content, residual ripple may be present

at the output depending upon the low frequency content

of the modulated RF signal. For example, when 4-carrier

Output Interface

The output buffer ampliﬁer of the LT5570 is shown in

Figure 9. This push-pull buffer ampliﬁer can source 5mA

current to the load and sink 2.5mA current from the load.

Theoutputimpedanceisdeterminedprimarilybythe100Ω

series resistor connected to the buffer ampliﬁer. This will

prevent any over-stress on the internal devices in case the

output is shorted to ground.

WCDMA is applied at the RF input, 36mV

(about

RMS

1dB) ripple is present at the output. This ripple can be

reduced with a larger ﬁltering capacitor C1 at the expense

of a slower transient response.

The –3dB bandwidth of the buffer ampliﬁer is about

2.4MHz and the full-scale rise/fall time can be as fast as

5570f

13

LT5570

APPLICATIONS INFORMATION

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

200

160

120

80

AT 2140MHZ, P = 10dBm

IN

RF

PULSE

OFF

RF

PULSE

OFF

RF PULSE ON

V

CC

40

0

EN

–40

–80

–120

–160

–200

100k

WITH FILTERING

WITHOUT

FILTERING

0

10 20 30 40 50 60 70 80 90 100

5570 F11

TIMES (μs)

5570 F10

Figure 10. Residual ripple, Output Transient

Times with Output Low-pass Filter

Figure 11. Enable Pin Simpliﬁed Circuit

Since the output ampliﬁer of the LT5570 is capable of driv-

ing an arbitrary capacitive load, the residual ripple can be

In general, the rise time of the LT5570 is much shorter

than the fall time. However, when the output RC ﬁlter is

used, the rise time is dominated by the time constant of

this ﬁlter. Accordingly, the rise time becomes very similar

to the fall time.

ﬁltered at the output with a series resistor R and a large

SS

shunt capacitor C

. See Figure 9. This lowpass ﬁlter

LOAD

also reduces the output noise by limiting the output noise

bandwidth. When this RC network is designed properly,

a fast output transient response can be maintained with

Enable Interface

reduced residual ripple. We can estimate C

with an

LOAD

A simpliﬁed schematic of the EN Pin interface is shown

in Figure 11. The enable voltage necessary to turn on the

LT5570 is 2V. To disable or turn off the chip, this voltage

should be below 1V. It is important that the voltage applied

output voltage swing of 1.8V at 2140MHz. In order that

the maximum 2.5mA sinking current not limit the fall time

(about 8μS), C

can be chosen as follows.

LOAD

to the EN pin should never exceed V by more than 0.3V.

C

= 2.5mA • approximate additional time/1.8V

CC

LOAD

Otherwise, the supply current may be sourced through

the upper ESD protection diode connected at the EN pin.

Under no circumstances should voltage be applied to the

= 2.5mA • 0.25μs/1.8V = 347pF

Once C is determined, R can be chosen properly

LOAD

SS

to form a RC lowpass ﬁlter with a corner frequency of

EN Pin before the supply voltage is applied to the V pin.

CC

2π/(R •C ).Using4-carrierW-CDMAasanexample,

SS LOAD

If this occurs, damage to the IC may result.

Figure 10 shows the residual ripple is reduced to half from

36mV

with R = 4.7k and C

= 330pF, while the

RMS

SS

LOAD

fall time is slightly increased to 8.8μS.

5570f

14

LT5570

PACKAGE DESCRIPTION

DD Package

10-Lead Plastic DFN (ꢀmm × ꢀmm)

(Reference LTC DWG # 05-08-1699)

R = 0.115

TYP

6

0.38 p 0.10

10

0.675 p0.05

3.50 p0.05

2.15 p0.05 (2 SIDES)

1.65 p0.05

3.00 p0.10

(4 SIDES)

1.65 p 0.10

(2 SIDES)

PIN 1

PACKAGE

OUTLINE

TOP MARK

(SEE NOTE 6)

(DD) DFN 1103

5

1

0.25 p 0.05

0.50 BSC

0.75 p0.05

0.200 REF

0.25 p 0.05

0.50

BSC

2.38 p0.10

(2 SIDES)

2.38 p0.05

(2 SIDES)

0.00 – 0.05

BOTTOM VIEW—EXPOSED PAD

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

NOTE:

1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).

CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE

TOP AND BOTTOM OF PACKAGE

5570f

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LT5570

RELATED PARTS

PART NUMBER

Infrastructure

LT5514

DESCRIPTION

COMMENTS

Ultralow Distortion, IF Ampliﬁer/ADC Driver

with Digitally Controlled Gain

850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range

LT5515

LT5516

1.5GHz to 2.5GHz Direct Conversion Quadrature 20dBm IIP3, Integrated LO Quadrature Generator

Demodulator

0.8GHz to 1.5GHz Direct Conversion Quadrature 21.5dBm IIP3, Integrated LO Quadrature Generator

Demodulator

LT5517

LT5518

40MHz to 900MHz Quadrature Demodulator

1.5GHz to 2.4GHz High Linearity Direct

Quadrature Modulator

21dBm IIP3, Integrated LO Quadrature Generator

22.8dBm OIP3 at 2GHz, –158.2dBm/Hz Noise Floor, 50Ω Single-Ended RF and LO

Ports, 4-Channel W-CDMA ACPR = –64dBc at 2.14GHz

LT5519

LT5520

LT5521

LT5522

LT5524

LT5525

LT5526

LT5527

LT5528

LT5557

0.7GHz to 1.4GHz High Linearity Upconverting

Mixer

17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω Matching,

Single-Ended LO and RF Ports Operation

1.3GHz to 2.3GHz High Linearity Upconverting

Mixer

15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω Matching,

Single-Ended LO and RF Ports Operation

24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, Single-Ended LO

Port Operation

10MHz to 3700MHz High Linearity

Upconverting Mixer

600MHz to 2.7GHz High Signal Level

Downconverting Mixer

4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω Single-Ended RF

and LO Ports

450MHz Bandwidth, 40dBm OIP3, 4.5dB to 27dB Gain Control

Low Power, Low Distortion ADC Driver with

Digitally Programmable Gain

High Linearity, Low Power Downconverting

Mixer

High Linearity, Low Power Downconverting

Mixer

400MHz to 3.7GHz High Signal Level

Downconverting Mixer

Single-Ended 50Ω RF and LO Ports, 17.6dBm IIP3 at 1900MHz, I = 28mA

CC

3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB, I = 28mA,

CC

–65dBm LO-RF Leakage

IIP3 = 23.5dBm and NF = 12.5dBm at 1900MHz, 4.5V to 5.25V Supply, I = 78mA,

CC

Conversion Gain = 2dB

1.5GHz to 2.4GHz High Linearity Direct

Quadrature Modulator

21.8dBm OIP3 at 2GHz, –159.3dBm/Hz Noise Floor, 50Ω, 0.5V Baseband

DC

Interface, 4-Channel W-CDMA ACPR = –66dBc at 2.14GHz

400MHz to 3.8GHz, 3.3V High Signal Level

Downconverting Mixer

IIP3 = 23.7dBm at 2600MHz, 23.5dBm at 3600MHz, I = 82mA at 3.3V

CC

LT5560

LT5568

Ultra-Low Power Active Mixer

700MHz to 1050MHz High Linearity Direct

Quadrature Modulator

10mA Supply Current, 10dBm IIP3, 10dB NF, Usable as Up- or Down-Converter.

22.9dBm OIP3 at 850MHz, –160.3dBm/Hz Noise Floor, 50Ω, 0.5V Baseband

DC

Interface, 3-Ch CDMA2000 ACPR = –71.4dBc at 850MHz

LT5572

LT5575

1.5GHz to 2.5GHz High Linearity Direct

Quadrature Modulator

800MHz to 2.7GHz High Linearity Direct

Conversion I/Q Demodulator

21.6dBm OIP3 at 2GHz, –158.6dBm/Hz Noise Floor, High-Ohmic 0.5V Baseband

DC

Interface, 4-Ch W-CDMA ACPR = –67.7dBc at 2.14GHz

50Ω, Single-Ended RF and LO Inputs. 28dBm IIP3 at 900MHz, 13.2dBm P1dB,

0.04dB I/Q Gain Mismatch, 0.4° I/Q Phase Mismatch

RF Power Detectors

LTC^®5505

LTC5507

LTC5508

LTC5509

RF Power Detectors with >40dB Dynamic Range 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply

100kHz to 1000MHz RF Power Detector

300MHz to 7GHz RF Power Detector

300MHz to 3GHz RF Power Detector

100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply

44dB Dynamic Range, Temperature Compensated, SC70 Package

36dB Dynamic Range, Low Power Consumption, SC70 Package

LTC5530

LTC5531

LTC5532

300MHz to 7GHz Precision RF Power Detector Precision V

Offset Control, Shutdown, Adjustable Gain

Offset Control, Shutdown, Adjustable Offset

Offset Control, Adjustable Gain and Offset

OUT

LT5534

50MHz to 3GHz Log RF Power Detector with

60dB Dynamic Range

1dB Output Variation over Temperature, 38ns Response Time, Log Linear

Response

LTC5536

LT5537

Precision 600MHz to 7GHz RF Power Detector 25ns Response Time, Comparator Reference Input, Latch Enable Input,

with Fast Comparator Output

–26dBm to +12dBm Input Range

Wide Dynamic Range Log RF/IF Detector

Low Frequency to 1GHz, 83dB Log Linear Dynamic Range

5570f

LT 1107 • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LT5570IDD-PBF
厂家：	Linear
描述：	Fast Responding, 40MHz to 2.7GHz Mean-Squared Power Detector 快速响应， 40MHz至2.7GHz的均方功率检测器
文件：	总16页 (文件大小：259K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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