GRAYCHIP, INC.

- 11 -

JUNE 22, 1998

GC3021 MIXER AND CARRIER REMOVAL CHIP

DATA SHEET

This document contains information which may be changed at any time without notice

2.12

DATA DELAYS

The data delay through the chip in input clock cycles is shown in Table 2 below.

2.13

POWER DOWN AND KEEP ALIVE CIRCUIT

This circuit is used to either power down the chip or to prevent excess power consumption when

the external clock is disconnected. In the power down mode the circuit selects a 1 KHz internal oscillator as

the chip’s internal clock, thereby reducing the chip’s power consumption down to a few milliwatts. In the

keep alive mode the chip detects when the clock has been inactive for one or two milliseconds and then

switches to the 1 KHz internal oscillator. This ensures that the chip’s internal dynamic nodes do not float to

middle voltages, a condition which can cause excessive power draw.

2.14

DIAGNOSTICS

The sync counter can be used as an input sync and data source in order to perform diagnostics.

The diagnostic outputs are captured in the snapshot RAM and compared with predicted results. The whole

chip except for the I/O pads, the high speed input circuit and the output format circuit can be checked this

way. Section 6.6 tabulates the diagnostic configurations and their expected snapshot outputs.

Table 2: DATA DELAYS

FROM

TO

DELAY

MODE

I, Q

SI, SQ

15

OUTSEL=1

I, Q

I, Q (even/odd)

13

OUTSEL=0