The HSP50214B Programmable Downconverter converts

digitized IF data into filtered baseband data which can be

processed by a standard DSP microprocessor. The

Programmable Downconverter (PDC) performs down

conversion, decimation, narrowband low pass filtering, gain

scaling, resampling, and Cartesian to Polar coordinate

conversion.

The 14-bit sampled IF input is down converted to baseband

by digital mixers and a quadrature NCO, as shown in the

Block Diagram. A decimating (4 to 32) fifth order Cascaded

Integrator-Comb (CIC) filter can be applied to the data

before it is processed by up to 5 decimate-by-2 halfband

filters. The halfband filters are followed by a 255-tap

programmable FIR filter. The output data from the

programmable FIR filter is scaled by a digital AGC before

being re-sampled in a polyphase FIR filter. The output

section can provide seven types of data: Cartesian (I, Q),

polar (R, θ), filtered frequency (dθ/dt), Timing Error (TE), and

AGC level in either parallel or serial format.

Features

• Up to 65MSPS Front-End Processing Rates (CLKIN) and

55MHz Back-End Processing Rates (PROCCLK)

Clocks May Be Asynchronous

• Processing Capable of >100dB SFDR

• Up to 255-Tap Programmable FIR

• Overall Decimation Factor Ranging from 4 to 16384

• Output Samples Rates to ≅12.94MSPS with Output

Bandwidths to ≅ 982kHz Lowpass

• 32-Bit Programmable NCO for Channel Selection and

Carrier Tracking

• Digital Resampling Filter for Symbol Tracking Loops and

Incommensurate Sample-to-Output Clock Ratios

• Digital AGC with Programmable Limits and Slew Rate to

Optimize Output Signal Resolution; Fixed or Auto Gain

Adjust

• Serial, Parallel, and FIFO 16-Bit Output Modes

• Cartesian to Polar Converter and Frequency Discriminator

for AFC Loops and Demodulation of AM, FM, FSK, and

DPSK

• Input Level Detector for External I.F. AGC Support

• Pb-Free Plus Anneal Available (RoHS Compliant)

Applications

• Single Channel Digital Software Radio Receivers

• Base Station Rx’s: AMPS, NA TDMA, GSM, and CDMA

• Compatible with HSP50210 Digital Costas Loop for PSK

Reception

• Evaluation Platform Available