A communications radio or transceiver having an extended upper operating frequency limit of at least 6 GHz. The radio includes a first IF conversion stage for receiving and downconverting a RF input signal to a first IF signal, and a second IF conversion stage for downconverting the first IF signal to a second IF signal. The first and the second conversion stages each have adjustable first and second attenuators, a serial peripheral interface (SPI) for controlling the attenuators in response to command words, a mixer coupled to an output of the second attenuator, and a buffer for applying a local oscillator (LO) signal to an input of the mixer. Each conversion stage is in the form of an integrated circuit chip. Component devices of each chip and electrical connections between the components, are dimensioned so that the chip has a 6 GHz upper frequency limit.