U4314B

The U4314B is a monolithic Integrated Circuit in bipolar technology for low current super-heterodyne receivers. It can be used as a logarithmic Received Signal Strength Indicator (RSSI) or as a logarithmic AM demodulator. U4314B's bandwidth is optimized for intermediate frequencies of 9 to 10.7 MHz (see figure 9).

U4314B's low current consumption and wide power supply voltage range make this IC predestined to add a temperature compensated field strength indication to new or existing receiver or instrumentation designs, missing such a function.
U4314B can also be used as a logarithmic AM demodulator.

U4314B's dynamic range in excess of 60 dB (see figure 10) supports a receiver design without the need of an automatic gain
control (AGC). The usable data rate of U4314B is up to several hundred kBauds. TU4314B applications are keyless entry
and alarm systems for cars and buildings.

The U4314B supports a superhet receiver design with less than 1 mA total current consumption, which is a  peremptory requirement claimed by international car manufacturers. As this IC needs only 3.0 V supply voltage,the front end may be a stacked design of U4314B in order to reach this extremely low total receiver current consumption.

A proposal for a discrete RF front end with a surface acoustic wave (SAW) resonator based local oscillator special low current UHF-transistors like S822T or S852T can be found in the application notes ANT012 and ANT013.