The RF2423 is a monolithic integrated transmitter IC capable of universal direct modulation for UHF AM, PM, or compound carriers. The transmitter may be used stand-alone for applications requiring not more than 100mW output power, or may be used to drive a final power amplifier. The maximum output level is 100mW, and is adjustable over a 25dB range by a single positive voltage. This low-cost IC implements differential amplifiers for the modulation inputs, 90 degree carrier phase shift network, carrier limiting amplifiers, two matched doubly-balanced mixers, variable gain summing amplifier for level control, and 100mW linear (class AB) output amplifier.