| 摘要 |
A wireless signal transmission circuit of a short-range wireless communication system is provided to be capable of easily controlling an amplification rate without being affected by power and temperature changes, by using the fact that transconductance has an independent feature from temperature and power voltage, when an MOSFET(Metal Oxide Semiconductor Field Effect Transistor) operates in a linear region. A bias control circuit(300) comprises the followings. A current mirror circuit(302) consists of a PMOS1 and a PMOS2. An operational amplifier(OP amp1) outputs differential amplification signals by receiving an external current source(Iext) connected to one side of the mirror circuit(302), an external current source(Iext) outputted to the other side of the mirror circuit(302), and an external voltage(Vref). An NMOS1 receives the differential amplification signals through a gate(G), while a drain(D) is connected to the other side of the mirror circuit(302). An NMOS2 receives the external voltage(Vref) through a gate(G) to output a voltage(V.sub.DS) between a drain(D) and a source as a gain control signal(Vagc), while the drain(D) is connected to a source(S) of the NMOS1.
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