Abstract: A voltage-to-current converter is described. In one embodiment, the voltage-to-current converter includes an operational amplifier, where a first input of the operational amplifier is coupled to a first node and a second input of the operational amplifier is coupled to a reference voltage. The input voltage is connected to the first node through a resistor which generates the input current. The voltage-to-current converter also includes a first transistor coupled to a first node and to an output of the operational amplifier, where the input current flows through the first transistor. The voltage-to-current converter also includes a second transistor coupled to the first transistor, to the output of the operational amplifier, and to an output node, where an output current flows through the second transistor. The first and second transistors constitute a current mirror to provide additional current gain for the output current.

Abstract: The invention is a system and method for sharing components of a single-path receiver or transmitter system multiple antennas. Specifically, according to one embodiment of the present invention, multiple antennas simultaneously share an analog-to-digital converter unit. The signal from one antenna is downconverted to a positive frequency band while the signal from another antenna is downconverted to a negative frequency band, allowing the signals to be processed by the analog-to-digital converter unit with minimal interference between signals and without the need for time-periodic switching. According to another embodiment of the present invention, multiple antennas simultaneously share a digital-to-analog converter unit.

Abstract: The invention is a system and method for sharing components of a single-path receiver or transmitter system multiple antennas. Specifically, according to one embodiment of the present invention, multiple antennas simultaneously share an analog-to-digital converter unit. The signal from one antenna is downconverted to a positive frequency band while the signal from another antenna is downconverted to a negative frequency band, allowing the signals to be processed by the analog-to-digital converter unit with minimal interference between signals and without the need for time-periodic switching. According to another embodiment of the present invention, multiple antennas simultaneously share a digital-to-analog converter unit.

Abstract: A variable gain amplifier includes a Gilbert cell multiplier cell having a pair of bipolar input transistors and a pair of bipolar output transistors. A bias circuit provides a first bias current to the input transistors and a second bias current to the output transistors, the ratio of the second to the first bias current determining the gain of the multiplier cell. The bias circuit couples the first and second bias currents to the emitters of the input and output transistors and references these currents to ground, which provides excellent supply rejection. Additionally, high beta immunity is achieved by increasing the ratio of the second bias current to the first bias current by subtracting a current from the first bias current substantially equal to the base currents of the output transistors.