AD6636CBCZ Analog Devices Inc, AD6636CBCZ Datasheet - Page 33

• Manufacturer Part Number: AD6636CBCZ
• Description: IC DIGITAL DWNCONV 4CH 256CSPBGA
• Manufacturer: Analog Devices Inc
• Series: AD6636r

Specifications of AD6636CBCZ

• Rf Type: Cellular, CDMA2000, EDGE, GPRS, GSM
• Number Of Mixers: 1
• Secondary Attributes: Down Converter
• Current - Supply: 450mA
• Voltage - Supply: 3 V ~ 3.6 V
• Package / Case: 256-CSPBGA
• Brief Features: 4/6 Independent Wideband Processing Channel, Quadrature Correction & DC Correction For Complex Input
• Supply Voltage Range: 1.7V To 1.9V
• Operating Temperature Range: -40°C To +85°C
• Ic Function: Digital Down Converter (DDC)
• Rohs Compliant: Yes
• Pin Count: 256
• Screening Level: Industrial
• Package Type: CSPBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency: -
• Gain: -
• Noise Figure: -
• Lead Free Status / Rohs Status: Compliant

The filter input sample rate is the same as the FIR2 filter output
rate and is given by one of the following equations:
If HB1 is bypassed,
If HB1 is not bypassed,
where:
f
f
f
The input to the filter has a maximum of 75 MHz. When not
bypassed, the maximum output rate is 37.5 MHz.
The filter has a ripple of 0.00075 dB and rejection of 81 dB. For
an alias rejection of 81 dB, the alias-protected bandwidth is 33%
of the filter input sample rate. The bandwidth of the filter for a
ripple of 0.00075 dB is the same as alias-protected bandwidth,
due to the nature of half-band filters. The 3 dB bandwidth of
this filter is 47% of the filter input sample rate. For example, if
the sample rate into the filter is 25 MHz, then the alias-
protected bandwidth of the HB2 filter is 8.25 MHz (33% of
25 MHz). If the bandwidth of the required carrier is greater
than 8.25 MHz, then HB2 may not be useful.
HB1
FIR2
HB2
–100.00
–110.00
–120.00
is the input rate of the HB1 filter.
is the input rate of the HB2 filter.
–19.99
–29.99
–39.99
–49.99
–60.00
–70.00
–80.00
–90.00
is the input rate of the FIR2 filter.
–9.99
f
f
HB2
HB2
0.01
Figure 35. HB2 Filter Response to the Input Rate of the Filter
= f
= f
0
FIR2
FIR2
0.1
= f
=
f
HB1
FRACTION OF HB2 INPUT SAMPLE RATE
0.2
HB1
2
0.3
0.34
0.4
0.5
0.6
0.66
0.7
HB2 RESPONSE
0.8
0.9
–65
Rev. A | Page 33 of 80
INTERMEDIATE DATA ROUTER
Following the FIR-HB cascade filters is the intermediate data
router. This data router consists of muxes that allow the I and Q
data from any channel front end (input port + NCO + CIC +
FIR-HB) to be processed by any channel back end (MRCF +
DRCF + CRCF). The choice of channel front end is made by
programming a 3-bit MRCF data select word in the MRCF
control register. The valid values for this word and their
corresponding settings are listed in Table 18.
Table 18. Data Router Select Settings
MRCF Data Select [2:0]
000
001
010
011
1x0
1x1
Allowing different channel back ends to select different channel
front ends is useful in the polyphase implementation of filters.
When multiple AD6636 channels are used to process a single
carrier, a single-channel front end feeds more than one channel
back end. After processing through the channel back ends (RCF
filters), the data is interleaved back from the polyphased channels.
MONORATE RAM COEFFICIENT FILTER (MRCF)
The MRCF is a programmable sum-of-products FIR filter. This
filter block comes after the first data router and before the
DRCF and CRCF programmable filters. It consists of a maximum
of eight taps with 6-bit programmable coefficients. Note that this
block does not decimate and is used as a helper filter for the
DRCF and CRCF filters that follow in the signal chain.
The number of filter taps that are to be calculated is program-
mable using the 3-bit number-of-taps word in the MRCF
control register of the channel under consideration. The 3-bit
word programmed is one less than the number of filter taps.
The coefficients themselves are programmed in eight MRCF
Figure 36. Composite Response of FIR2 and HB2 filters to their Input Rates
–100.00
–110.00
–120.00
–19.99
–29.99
–39.99
–49.99
–60.00
–70.00
–80.00
–90.00
–9.99
0.01
0
0.1
FRACTION OF HB2 INPUT SAMPLE RATE
0.2
0.3
0.34
0.4
Data Source
Channel 0
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
0.5
0.6
0.66
0.7
FIR2 + HB2
RESPONSE
0.8
0.9
AD6636
–90