AD6620
–3–REV. A
Following CIC2 is the second fixed-coefficient decimating filter.
This filter, CIC5, further reduces the sample rate by a program-
mable ratio from 1 to 32. The data rate out of CIC5, f
SAMP5
, is
determined by the decimation factors of M
CIC5
and M
CIC2
.
Each CIC stage is a FIR filter whose response is defined by the
decimation rate. The purpose of these filters is to reduce the
data rate of the incoming signal so that the final filter stage, a FIR
RAM coefficient sum-of-products filter (RCF), can calculate
more taps per output. As shown in Figure 1, on-chip multiplex-
ers allow both CIC filters to be bypassed if a multirate clock
is used.
The fourth stage is a sum-of-products FIR filter with program-
mable 20-bit coefficients, and decimation rates programmable
from 1 to 32. The RAM Coefficient FIR Filter (RCF in Figure
1) can handle a maximum of 256 taps.
The overall filter response for the AD6620 is the composite of
all three cascaded decimating filters: CIC2, CIC5, and RCF. Each
successive filter stage is capable of narrower transition band-
widths but requires a greater number of CLK cycles to calculate
the output. More decimation in the first filter stage will minimize
overall power consumption. Data comes out via a parallel port
or a serial interface.
Figure 2 illustrates the basic function of the AD6620: to select
and filter a single channel from a wide input spectrum. The
frequency translator “tunes” the desired carrier to baseband.
CIC2 and CIC5 have fixed order responses; the RCF filter
provides the sharp transitions. More detail is provided in later
sections of the data sheet.
f
S
/2 3f
S
/8 5f
S
/16 f
S
/4 3f
S
/16 f
S
/8 f
S
/16
DC
f
S
/16 f
S
/8 3f
S
/16 f
S
/4 5f
S
/16 f
S
/23f
S
/8
SIGNAL OF
INTEREST
SIGNAL OF INTEREST "IMAGE"
WIDEBAND INPUT SPECTRUM
(f
samp/
2 TO f
samp/
2)
D'
C'
B'
A'
A
C
B
D
Figure 2a. Wideband Input Spectrum (e.g., 30 MHz from High-Speed ADC)
f
S
/2 3f
S
/8 5f
S
/16 f
S
/4 3f
S
/16 f
S
/8 f
S
/16 DC f
S
/16 f
S
/8 3f
S
/16 f
S
/4 5f
S
/16 f
S
/23f
S
/8
AFTER FREQUENCY TRANSLATION
NCO "TUNES" SIGNAL TO BASEBAND
A
B
C
D
D'
C'
B'
A'
Figure 2b. Frequency Translation (e.g., Single 1 MHz Channel Tuned to Baseband)
0
10
20
30
40
50
60
70
80
90
100
110
120
130
CIC2, CIC5, AND RCF
dBc
FREQUENCY
Figure 2c. Baseband Signal is Decimated and Filtered by CIC2, CIC5, RCF
–4–
REV. A
AD6620–SPECIFICATIONS
RECOMMENDED OPERATING CONDITIONS
Test AD6620AS
Parameter Level Min Typ Max Unit
VDD I 3.0 3.3 3.6 V
T
AMBIENT
IV –40 +25 +85 °C
ELECTRICAL CHARACTERISTICS
Test AD6620AS
Parameter (Conditions) Temp Level Min Typ Max Unit
LOGIC INPUTS
1, 2, 3, 4, 5, 6, 7
(NOT 5 V TOLERANT)
Logic Compatibility Full 3.3 V CMOS
Logic “1” Voltage Full I 2.0 VDD + 0.3 V
Logic “0” Voltage Full I –0.3 0.8 V
Logic “1” Current Full I 1 10 µA
Logic “0” Current Full I 1 10 µA
Input Capacitance 25°CV 4 pF
LOGIC OUTPUTS
2, 4, 7, 8, 9, 10, 11
Logic Compatibility Full 3.3 V CMOS/TTL
Logic “1” Voltage (I
OH
= 0.5 mA) Full I 2.4 VDD – 0.2 V
Logic “0” Voltage (I
OL
= 1.0 mA) Full I 0.2 0.4 V
IDD SUPPLY CURRENT
CLK = 20 MHz
12
Full V 52 mA
CLK = 65 MHz
13
Full I 167 227 mA
Reset Mode
14
Full I 1 mA
POWER DISSIPATION
CLK = 20 MHz
12
Full V 170 mW
CLK = 65 MHz
13
Full I 550 750 mW
Reset Mode
14
Full I 3.3 mW
NOTES
1
Input-Only Pins: CLK, RESET, IN[15:0], EXP[2:0], A/B, PAR/SEL.
2
Bidirectional Pins: SYNC_NCO, SYNC_CIC, SYNC_RCF.
3
Microinterface Input Pins: DS (RD), R/W (WR), CS.
4
Microinterface Bidirectional Pins: A[2:0], D[7:0].
5
JTAG Input Pins: TRST, TCK, TMS, TDI.
6
Serial Mode Input Pins: SDI, SBM, WL[1:0], AD, SDIV[3:0].
7
Serial Mode Bidirectional Pins: SCLK, SDFS.
8
Output Pins: OUT[15:0], DV
OUT
, A/B
OUT
, I/Q
OUT
.
9
Microinterface Output Pins: DTACK (RDY).
10
JTAG Output Pins: TDO.
11
Serial Mode Output Pins: SDO, SDFE.
12
Conditions for IDD @ 20 MHz. M
CIC2
= 2, M
CIC5
= 2, M
RCF
= 1, 4 RCF taps of alternating positive and negative full scale.
13
Conditions for IDD @ 65 MHz. M
CIC2
= 2, M
CIC5
= 2, M
RCF
= 1, 4 RCF taps of alternating positive and negative full scale.
14
Conditions for IDD in Reset (RESET = 0).
Specifications subject to change without notice.
–5–REV. A
AD6620
TIMING CHARACTERISTICS
(C
LOAD
= 40 pF All Outputs)
Test AD6620AS
Parameter (Conditions) Temp Level Min Typ Max Unit
CLK Timing Requirements:
t
CLK
CLK Period Full I 14.93
1
ns
t
CLK
CLK Period Full I 15.4 ns
t
CLKL
CLK Width Low Full IV 7.0 0.5 × t
CLK
ns
t
CLKH
CLK Width High Full IV 7.0 0.5 × t
CLK
ns
Reset Timing Requirements:
t
RESL
RESET Width Low Full I 30.0 ns
Input Data Timing Requirements:
t
SI
Input
2
to CLK Setup Time Full IV –1.0 ns
t
HI
Input
2
to CLK Hold Time Full IV 6.5 ns
Parallel Output Switching Characteristics:
t
DPR
CLK to OUT[15:0] Rise Delay Full IV 8.0 19.5 ns
t
DPF
CLK to OUT[15:0] Fall Delay Full IV 7.5 19.5 ns
t
DPR
CLK to DV
OUT
Rise Delay Full IV 6.5 19.0 ns
t
DPF
CLK to DV
OUT
Fall Delay Full IV 5.5 11.5 ns
t
DPR
CLK to IQ
OUT
Rise Delay Full IV 7.0 19.5 ns
t
DPF
CLK to IQ
OUT
Fall Delay Full IV 6.0 13.5 ns
t
DPR
CLK to AB
OUT
Rise Delay Full IV 7.0 19.5 ns
t
DPF
CLK to AB
OUT
Fall Delay Full IV 5.5 13.5 ns
SYNC Timing Requirements:
t
SY
SYNC
3
to CLK Setup Time Full IV –1.0 ns
t
HY
SYNC
3
to CLK Hold Time Full IV 6.5 ns
SYNC Switching Characteristics:
t
DY
CLK to SYNC
4
Delay Time Full V 7.0 23.5 ns
Serial Input Timing:
t
SSI
SDI to SCLKt Setup Time Full IV 1.0 ns
t
HSI
SDI to SCLKt Hold Time Full IV 2.0 ns
t
HSRF
SDFS to SCLKu Hold Time Full IV 4.0 ns
t
SSF
SDFS to SCLKt Setup Time
5
Full IV 1.0 ns
t
HSF
SDFS to SCLKt Hold Time
5
Full IV 2.0 ns
Serial Frame Output Timing:
t
DSE
SCLKu to SDFE Delay Time Full IV 3.5 11.0 ns
t
SDFEH
SDFE Width High Full V t
SCLK
ns
t
DSO
SCLKu to SDO Delay Time Full IV 4.5 11.0 ns
SCLK Switching Characteristics, SBM = “1”:
t
SCLK
SCLK Period
4
Full I 2 × t
CLK
ns
t
SCLKL
SCLK Width Low Full V 0.5 × t
SCLK
ns
t
SCLKH
SCLK Width High Full V 0.5 × t
SCLK
ns
t
SCLKD
CLK to SCLK Delay Time Full V 6.5 13.0 ns
Serial Frame Timing, SBM = “1”:
t
DSF
SCLKu to SDFS Delay Time Full IV 1.0 4.0 ns
t
SDFSH
SDFS Width High Full V t
SCLK
ns
SCLK Timing Requirements, SBM = “0”:
t
SCLK
SCLK Period Full I 15.4 ns
t
SCLKL
SCLK Width Low Full IV 0.4 × t
SCLK
0.5 × t
SCLK
ns
t
SCLKH
SCLK Width High Full IV 0.4 × t
SCLK
0.5 × t
SCLK
ns
NOTES
1
This specification valid for VDD >= 3.3 V. t
CLKL
and t
CLKH
still apply.
2
Specification pertains to: IN[15:0], EXP[2:0], A/B.
3
Specification pertains to: SYNC_NCO, SYNC_CIC, SYNC_RCF.
4
SCLK period will be 2 × t
CLK
when AD6620 is Serial Bus Master (SBM = 1) depending on the SDIV word.
5
SDFS setup and hold time must be met, even when configured as outputs, since internally the signal is sampled at the pad.
Specifications subject to change without notice.

AD6620ASZ

Mfr. #:
Manufacturer:
Analog Devices Inc.
Description:
Up-Down Converters 65MSPS Digital Rcvr Signal Processor
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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