MC13142D View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

MC13142D

Low Power DC – 1.8 GHz LNA, Mixer and VCO

Motorola => Freescale 

MC13142

CIRCUIT DESCRIPTION

General

The MC13142 is a low power LNA, double–balanced

Mixer, and VCO. This device is designated for use as the

frontend section in analog and digital FM systems such as

Digital European Cordless Telephone (DECT), PHS, PCS,

Cellular, UHF and 800 MHz Special Mobile Radio (SMR),

UHF Family Radio Services and 902 to 928 MHz cordless

telephones. It features a mixer linearity control to preset or

auto program the mixer dynamic range, an enable function

and a wideband IF so the IC may be used either as a down

converter or an up converter. Further details are covered in

the Pin by Pin Description which shows the equivalent

internal circuit and external circuit requirements.

Current Regulation/Enable

Temperature compensating voltage independent current

regulators are controlled by the enable function in which

“high” powers up the IC.

Low Noise Amplifier (LNA)

The LNA is internally biased at low supply current

(approximately 2.0 mA emitter current) for optimal noise

figure and gain. The LNA output is biased internally with a

600 Ω resistor to VCC. Input and output matching may be

achieved at various frequencies using few external

components. Matching the LNA for Maximum stable gain

(MSG) yields noise performance within a few tenths of a dB

of the minimum noise figure.

Mixer

The mixer is a double–balanced four quadrant multiplier

biased class AB allowing for programmable linearity control

via an external current source. An input third order intercept

point of 20 dBm may be achieved. All 3 ports of the mixer are

designed to work up to 1.8 GHz. The mixer has a 50 Ω

single–ended RF input and open collector differential IF

outputs. An on–board Local Oscillator transistor has the

emitter, base and collector pinned out to implement a low

phase noise VCO in various configurations. Additionally, a

buffered LO output is provided for operation with a frequency

synthesizer. The linear gain of the mixer is approximately

0 dB with a SSB noise figure of 12 dB in the IF output circuit

configuration shown in the application example.

Local Oscillator

The on–chip transistor operates with coaxial transmission

line or LC resonant elements to over 2.0 GHz. Biasing is

done with a temperature compensated current source in the

emitter and a collector to base internal resistor of 7.6 kΩ;

however, an RFC from VCC to base is recommended. The

application circuit shows a voltage controlled Clapp oscillator

operating at center frequency of 975 MHz.

MOTOROLA RF/IF DEVICE DATA

3

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