Ku Band Downconverter with Integrated Fractional-N PLL and VCO

The ADMV4640 is a microwave downconverter optimized for various satellite communication (SATCOM) user terminals operating in the 10.7 GHz to 12.7 GHz RF range.

The ADMV4640 local oscillator (LO) signal is generated internally via the on-chip Integer N (INT) synthesizer. The internal synthesizer enables LO frequency coverage from 8.7 GHz to 10.7GHz. The input RF signals from 10.7 GHz to 12.7 GHz are down converted to an output intermediate frequency (IF) of 1.4 GHz to 2.2 GHz. The chip includes filtering to reject the image band of 6.7 GHz to 8.7 GHz. The on-chip low noise amplifier includes a 6 dB step attenuator before the mixer to allow the user to trade off between lower noise figure and higher linearity. In addition, the chip includes a digital step attenuator at the IF output to provide up to 31 dB of gain control range with 1 dB steps to adjust for subsequent cable losses.

The digital serial peripheral interface (SPI) allows easy programming of the device. In addition to the digital SPI control, an analog control pin (RXMUTE) quickly powers down all circuits and places the receiver in standby mode for power saving. An analog general purpose input-output (AGPIO) pin can be used either as an input to be read by the on-chip analog-to-digital converter (ADC) or as an output for internal analog proportional to absolute temperature (PTAT) voltage. There are also three digital GPIO pins to output logic levels to control external devices using the SPI.

The ADMV4640 downconverter comes in a compact, thermally enhanced, 6 mm × 6 mm, 40-lead, lead frame chip scale package (LFCSP). The ADMV4640 operates over the −40°C to +85°C case temperature range.

Applications

* SATCOM user terminals

* X/Ku band to IF downconverter with integrated PLL

* RF input frequency range: 10.7 GHz to 12.7 GHz

* Internal LO frequency range: 8.7 GHz to 10.7 GHz

* Noise figure: 5.2 dB, minimum attenuation, LNA low gain mode

* Matched, 50 Ω, single-ended RF input and IF output