Analog Devices' ADRF670x provides a quadrature modulator and synthesizer solution within a small 6 mm × 6 mm footprint while requiring minimal external components. The ADRF670x is designed for RF outputs from 400 MHz to 1250 MHz. The low phase noise VCO and high performance quadrature modulator make the ADRF670x suitable for next generation communication systems requiring high signal dynamic range and linearity. The integration of the IQ modulator, PLL, and VCO provides for significant board savings and reduces the BOM and design complexity.
The integrated fractional-N PLL/synthesizer generates a 2× fLO input to the IQ modulator. The phase detector together with an external loop filter is used to control the VCO output. The VCO output is applied to a quadrature divider. To reduce spurious components, a sigma-delta (Σ-Δ) modulator controls the programmable PLL divider.
The IQ modulator has wideband differential I and Q inputs, which support baseband as well as complex IF architectures. The single-ended modulator output is designed to drive a 50 Ω load impedance and can be disabled. The ADRF670x is fabricated using an advanced silicon-germanium BiCMOS process. It is available in a 40-lead, exposed-paddle, Pb-free, 6 mm × 6 mm LFCSP package. Performance is specified from −40°C to +85°C. A lead-free evaluation board is available.