RF142 Просмотр технического описания (PDF) - Conexant Systems

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RF142

Heterojunction Bipolar Transistor Power Amplifier Dual-Band Controller for GSM and PCS Applications

Conexant Systems 

RF142

Power Amplifier Controller

Pin #

1

2

3

4

5

6

7

Name

GND1

VREF

VMP

VAPC+

VAPC–

ENABLE

RFPC+

8 RFPC–

9 GND2

10 VCC1

Table 1. RF142 Signal Description

Description

Ground

Output reference voltage

Midpoint voltage for gain shaper

Tx power control positive polarity

Tx power control negative polarity

Device enable (active high)

RF input to detector positive polarity

RF input to detector negative polarity

Ground

Power supply

Pin #

11

12

13

14

15

16

17

Name

NC

NC

CAP+

CAP–

AUX+

AUX–

BAND

18 VPCDCS

19 VPCGSM

20 VCC2

Description

No connect

No connect

Integrator time constant Cap+

Integrator time constant Cap–

Aux output +

Aux output –

Band select. High selects VPCDCS as the output control

pin; low selects VPCGSM as the output control pin.

1800 MHz/1900 MHz power amplifier control voltage

900 MHz power amplifier control voltage

Vcc for the output stage

BAND

VREF

VMP

Gain Shaper

AUX+

AUX–

Amp 1

Amp 2

Logarithmic

Detector

DC Bias

Circuitry

VPCGSM

VPCDCS

RFPC+

RFPC–

VCC2

VCC1

GND

CAP- CAP+ VAPC- VAPC+

ENABLE

C013

Figure 2. RF142 Block Diagram

Technical Description

The RF142 dual-band PA controller is designed to control HBT

PAs. It combines the functions of a broadband RF detector and

error amplifier/integrator to provide transmit burst control for

dual or multi-band HBT PAs. It has two separate dedicated

output stages and pins for GSM900MHz PAs and

GSM1800/1900 MHz PAs. The device, when connected to dual

or multi-band HBT PAs with a coupler, forms a loop to control

the transmit power in a dual or multi-band wireless application.

The transmit power is controlled by a single balanced analog

reference voltage input to the RF142.

The RF142 has low power consumption and operates off a

three-cell battery pack (2.7 V to 5.0 V). Extremely low standby

current of 20 µA maximizes the standby time of a GSM handset.

The absolute maximum ratings of the RF142 are provided in

Table 2, the operating conditions are specified in Table 3, and

electrical specifications are provided in Table 4. Figure 3 shows

the diagram for a typical application circuit using the RF142 PA

controller. Figure 4 shows the package dimensions for the 20-

pin TSSOP device and Figure 5 provides the tape and reel

dimensions.

RF Detector. An external RF coupler is required at the PA

output to couple the RF output from the PA to the RF logarithmic

detector input. The input to the logarithmic detector must be

within the range –40 dBm to +10 dBm. The coupled signal is fed

to the input of the RF power detector. The output from the

detector is a DC voltage that is proportional to the RF power (in

dBm) at the RFPC input to the device. The dynamic range of the

detector is 50 dB.

Integrating Error Amplifier. The integrating error amplifier

(Amp2) amplifies and integrates the voltage difference between

the detector output and the power control input, VAPC. The

integrator time constant is set by the two external capacitors

connected from AUX pins to the CAP pins.

2

September 7, 2000

Conexant

Proprietary Information and Specifications are Subject to Change

100774A

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