MCP37X10-200 12-Bit Single-Channel Evaluation Kit User’s Guide
DS50002511A-page 18
2016 Microchip Technology Inc.
2.2.4
Input/Output Optimization
2.2.4.1
OPTIMIZING THE CLOCK CONNECTION
The evaluation board does not come with a clock source for the device. The user must
provide a clock source in order to run this evaluation board. The user has the following
options:
• Using Microchip’s 200 MHz Clock Source Evaluation Boards:
- Microchip’s ADM00725 or ADM00791 evaluation boards may be connected to
the external clock SMA input (See
). These boards were developed
as an optimized clock source for Microchip’s High-Speed ADCs. For more
information, refer to the board web page.
• Using a signal generator:
- A clean and low-jitter clock signal can be connected to the external clock SMA
input. For the signal generation, Rohde & Schwarz
®
SMA100A or Agilent
Technologies HP8644B signal generators can be used. To ensure that a clean
and low-jitter clock signal is provided, the user should interpose a band-pass
filter to reduce the harmonics coming from the signal source. A 200 MHz
band-pass filter, such as KC4T-200M-10P-50-3A from TTE
®
Inc., is
recommended. A high-jitter or unfiltered clock source will reduce achievable
SNR at higher input frequencies.
• Using a Crystal Oscillator on the board:
- An unpopulated footprint is available on the board where the user can place a
crystal oscillator. For a single-ended clock, refer to the instructions in Example
1. For a differential clock, refer to the instructions in Example 2. The user may
also choose to place another type of clock as well. Note that the component
values given below are for example only and may vary depending on the
exact clock source used.
Example 1
A clock oscillator with a single-ended output may be populated on Y2. The use of a
Microchip oscillator is recommended, such as the MXT573ABC200M000 for a 200
MHz clock. In this case, proceed to make the following modifications:
1.
Remove R36
2.
Populate R89 with a 499
resistor
3.
Populate C106 with a 15 pF capacitor.
Example 2
A clock oscillator with a differential LVPECL output may be populated on Y2. The use
of a Microchip oscillator is recommended, such as the MXT575ABA200M000 for a 200
MHz clock. In this case, proceed to make the following modifications:
1.
Remove R36 and R136
2.
Populate R89 and R90 with a 210
resistor
3.
Populate C105 and C106 with a 22 pF capacitor.
2.2.4.2
OPTIMIZING THE ANALOG INPUT CONNECTION
The best way to evaluate the MCP37X10-200 device is to use a clean analog input
signal with as little noise as possible. The signal can be provided using a signal
generator, such as Rohde & Schwarz SMA100A or Agilent Technologies HP8644B,
and can be used along with a bandpass filter. The filter will help with filtering the
harmonic tones of the fundamental, as well as with reducing the phase noise of the
source. Two such filters that can be used are:
