Each upconverter and downconverter chip is highly integrated (see Figure 1), comprised of in phase (I) and quadrature phase (Q) mixers with on-chip quadrature phase-shifter configurable for direct conversion to/from the baseband (operable from dc to 6 GHz) or to/from an intermediate frequency (IF) that can operate from 800 MHz to 6 GHz. The upconverter RF output has an on-chip transmit driver amplifier with a voltage variable attenuator (VVA), while the downconverter’s RF input contains a low noise amplifier (LNA) and gain stage with a VVA. Both chips’ local oscillator (LO) chain consists of an integrated LO buffer, a frequency quadrupler, and a programmable band-pass filter. Most of the programmability and calibration functions are controlled via an SPI interface, making the ICs easily software configurable to a performance level that is unmatched.
An inside look at the ADMV1013 upconverter
The ADMV1013 offers two modes of frequency translation. One mode is direct upconversion from baseband I and Q to RF. In this I/Q mode, the baseband I and Q differential inputs can accept signals from dc up to 6 GHz, for instance, generated from a pair of high speed transmit digital-to-analog converters (DACs). These inputs have a configurable common-mode range from 0 V to 2.6 V; thus, they can accommodate the interface requirements of most DACs. So when a DAC with a certain common-mode voltage is chosen, the upconverter’s registers can be easily set to match the optimum bias for that VCM voltage, simplifying the interface design. The other mode is single-sideband upconversion to RF from complex IF inputs such as those signals generated by a quadrature digital upconverter device.