DC1398A-GA Linear Technology, DC1398A-GA Datasheet - Page 12

• Manufacturer Part Number: DC1398A-GA
• Description: BOARD EVAL LTM9001-GA
• Manufacturer: Linear Technology
• Type: Baseband Receiverr

Specifications of DC1398A-GA

• Design Resources: Demo Circuit 1398A Schematic
• Frequency: 0Hz ~ 300MHz
• Kit Contents: Board, Manual
• Features: LTM9001 16bit Receiver Subsystem, DC-10MHz LPF
• Tool / Board Applications: Wireless Connectivity-ZigBee, RF, Infrared, USB
• Development Tool Type: Hardware - Eval/Demo Board
• Mcu Supported Families: LTM9001
• For Use With/related Products: LTM9001
• Lead Free Status / RoHS Status: Not applicable / Not applicable

OPERATION
LTM9001-GA
The following sections describe in further detail the
functional operation of the LTM9001. The SiP technology
allows the LTM9001 to be customized and this is described
in the fi rst section. The remaining outline follows the basic
functional elements as shown in Figure 1.
SEMI-CUSTOM OPTIONS
The μModule construction affords a new level of fl exibility
in application-specifi c standard products. Standard ADC
and amplifi er components can be integrated regardless
of their process technology and matched with passive
components to a particular application. The LTM9001-AA,
on a separate data sheet, is confi gured with a 16-bit ADC
sampling at rates up to 130Msps. The amplifi er gain is
20dB with an input impedance of 200Ω and an input
range of 233mV
optimize the interface between the amplifi er output and the
ADC under these conditions. Additionally, there is a 2-pole
bandpass fi lter designed for 162.5MHz ±25MHz.
However, other options are possible through Linear
Technology’s semi-custom development program. Linear
Technology has in place a program to deliver other speed,
resolution, IF range, gain and fi lter confi gurations for a
wide range of applications. See Table 1 for the LTM9001
confi guration and potential options. These semi-custom
designs are based on existing ADCs and amplifi ers with
an appropriately modifi ed matching network. The fi nal
subsystem is then tested to the exact parameters defi ned
for the application. The fi nal result is a fully integrated,
accurately tested and reliable solution. For more details
on the semi-custom receiver subsystem program, contact
Linear Technology.
12
AMPLIFIER
Figure 1. Basic Functional Elements
P-P
. The matching network is designed to
NETWORK
INPUT
ADC
ADC
9001-GA F01
Note that not all combinations of options in Table 1 are
possible at this time and specifi ed performance may differ
signifi cantly from existing values. The higher speed options
support LVDS or CMOS outputs and are available on a
separate data sheet. This data sheet discusses CMOS only
versions which have a different pin assignment.
AMPLIFIER INFORMATION
The amplifi ers used in the LTM9001 are low noise and low
distortion fully differential ADC drivers. The amplifi ers are
very fl exible in terms of I/O coupling. They can be AC- or
DC-coupled at the inputs. Users are advised to keep the
input common mode voltage between 1V and 1.6V for
proper operation. If the inputs are AC-coupled, the input
common mode voltage is automatically biased. The input
signal can be either single-ended or differential with almost
no difference in distortion performance.
ADC INPUT NETWORK
The passive network between the amplifi er output stage
and the ADC input stage can be confi gured for bandpass
or lowpass response with different cutoff frequencies and
bandwidths. The LTM9001-GA, for example, implements
a 1-pole lowpass fi lter with 10MHz bandwidth. Note that
the fi lter attenuates the signal at 10MHz by 0.2dB, making
the overall gain of the subsystem 7.8dB.
For production test purposes the fi lter is designed to allow
DC inputs into the ADC.
CONVERTER INFORMATION
The analog-to-digital converter (ADC) is a CMOS pipelined
multistep converter with a front-end PGA. As shown in the
Functional Block Diagram, the converter has fi ve pipelined
ADC stages; a sampled analog input will result in a digitized
value seven cycles later (see the Timing Diagram section).
The encode input is differential for improved common
mode noise immunity.
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