Introduction

STV6111

2/4

Doc ID 022528 Rev 1

1

Introduction

In the STV6111 satellite tuner, on the RF input, there is a variable gain, low-noise amplifier

(VGLNA). The RF gain is monitored by an automatic gain control (AGC) circuit to ensure an

optimal signal level for the two mixers. Each mixer, which down-converts the signal to the

baseband, is followed by an AGC-controlled VGA, a low-pass filter and a second VGA.

The local oscillator signals are provided by an integrated fractional-N phase locked loop

(PLL), which contains an on-chip voltage-controlled oscillator meeting stringent phase noise

requirements. The PLL loop filter is partly integrated. The local oscillator frequencies are

programmable between 950 MHz and 2150 MHz.

The comparison frequency for the phase-frequency detector is generated by dividing the

crystal oscillator reference frequency. The crystal frequency may be within the range

15 MHz to 31 MHz depending on the application.

Features

Benefits

Variable gain low noise amplifier input structure

Allows flexible compromise between linearity and

noise figure allowing the most difficult signals to be

extracted in the most congested and noisy

conditions

Single flexible Xtal

Wide choice of crystal frequencies with robust

clock buffer to drive second tuners and

demodulators allowing eBoM savings

Fractional-N PLL

Low phase noise for low packet error rate under

extreme conditions (e.g. low symbol rates), fast

locking

High symbol rate support

Allows more efficient exploitation of Ku (up to

60 Msps) and Ka band (up to ~220 Msps) satellites