U4311B-FS

· Usable for amplitude- and frequency-modulated transmission systems
· Extremely low quiescent current (approximately 1 mA in standby mode due to wake-up concept)
· Wide power supply voltage range 3 to 13 V
· Sensitive IF amplifier for 10.7-MHz operating
· Logarithmic AM demodulator
· FM demodulator
· Monoflop output to wake up a microcontroller
· High-performance operational amplifier to realize a data recovering filter
· Non-inverting clamping comparator with amplitudedepending hysteresis for data regeneration

The U4311B-FS is well-suited to implement UHF remote control or data transmission systems, based on a lowcurrent
superheterodyne receiver concept. SAW-devices may be used in the transmitter's as well as in the receiver local oscillator. The front end should be a discrete circuit application with low-current UHF transistors such as S822T or S852T (Vishay Telefunken). The frequency of the local oscillator can be determined either by coaxial resonators or SAW devices. Due to the large SAW-resonator, tolerance an IF bandwidth - and in a FM system additionally the discriminator amplitude characteristic (see figure 28) - of 300 kHz or higher is proposed.

As the circuit needs only 3.0 V supply voltage for operation, the front end may be a stacked design in order to achieve a total receiver current consumption of approximately 1 mA. Figure 29 shows a principle receiver concept diagram.

The U4311B-FS is a monolithic integrated circuit in bipolar technology for low-current UHF remote control super-heterodyne receivers in amplitude- or frequencymodulated mode. Typical applications are keyless car lock-, alarm- or tele-control remote indication systems.Especially for automotive applications, U4311B-FS supports a superhet design with about 1 mA total current consumption as required by the car manufacturers.