A new mixer circuit using gate-controlled LPNP BJT

A new mixer circuit is proposed by using the novel gate-controlled lateral PNP (LPNP) device. A major advantage of this four terminal device is that its collector current I/sub c/ can also be controlled by applying a voltage V/sub G/ to the additional input gate terminal. The associated large-signal and small-signal characteristics, such as current gain h/sub FE/ and transconductance g/sub M/, show very strong non-linear features as a function of the gate voltage. Therefore, this new device is particularly suitable for a mixer circuit for possible applications to portable wireless communications. The primary experimental results show that the mixing outputs for an intermediate frequency (IF) of 0.5 MHz using this new mixer circuit have conversion gain of 5 dB to 12 dB for the input radio frequency (RF) signal ranges of up to 400 MHz. The signal-to-noise ratio of its mixing IF output is about 50 dB. Another potential feature of this mixer circuit is that it can be easily integrated with other required signal processing circuits using a BiCMOS technology, and with no additional processing steps.