Mathcad - ee217projtodonew2.mcd

∆f: The frequency spacing of the undesired signals from the desired signals. This is used for
distortion calculations.
S11: The maximum desired S11 is determined by the external filter connected to the LNA.
This external filter relies on the low noise amplifier to have a certain impedance to provide given
filtering characteristics.
Gain: The minimum and maxmium desired gain constraints are set by the noise of the
system behind the amplifier.
V DD : The supply voltage is set by the end-of life voltage of three Lithium Ion AA batteries
plus some loss for a voltage regulator. Normally they are 1.5V each, which corresponds to a
normal operating voltage of 4.5V. At end of life they are 1V each, which corresponds to a 3V
supply. The voltage regulator output can vary up to 10%, which gives a minimum supply voltage
of 2.7V.
Temp: The normal operating temperature of the device is a room temperature of 27C plus
some die heating of 15C to due nonideal heat sinking. The actual operating temperature in a
worst case environment may vary between -30C and 105C, but was not added to the design
routine, because of time constraints.
Z bias : The bias impedance is chosen by the practical size limitation of an on-chip inductor to
be used as a bias choke. A 50nH inductor is assumed with a Q of 3 at 1.9 GHz.
K Factor: The desired minimum K factor is somewhat of a guess. In order to simultaneously
conjugate match the input and output ports of the device, the K factor must be greater than one.
If the K factor is set equal to one the real part of the conjugate matching impedance of the source
becomes zero ohms, which is infeasible. For this reason the K factor is set to a value somewhat
larger than one. Although the value was chosen with an educated guess, a real practical value
for K can be calculated by setting a lower limit to the input impedance or an upper limit to the
input matching network, and using it to solve for the K.
NF: The noise figure is determined by the value of the received signal when the cellular
phone is operated at it’s farthest distance from the base station. Here the noise level of the
receiver must be a significant value below the small desired signal.
IP 3 : The third order intercept point is a measure of the low noise amplifiers ability to reject
unwanted signals, such as another cellular phone. When the cellular phone is being used at it’s
greatest distance from base station the phone must be able distinguish the desired signal from
another cellular phone.
∆f 10 MHz Jammer Frequency Spacing
f 1900 MHz ω 2. π . f s j. ω
Frequency of Desired Signal
S 11goaldB 15 dB Input Match Requirement
IP 3goaldBm 10 dBm 3rd Order Intercept Point Requirement
G goaldB 13.5 dB G min 12 dB G max 15 dB Available Power Gain Requirement
Z bias 100 Ω j2 . . π . f 50
. nH Bias Impedance
K val 1.1 Desired In-band Stability Factor
V DD 2.7 V Supply Voltage
Temp 300 K Operating Temperature
N 40 Number of Devices in Parallel
10. mA
Bias Current
I C
The optimizer will find the best value for current and area. The entered values are used for
function testing purposes and graphing.
C/(N+I) Optimization Inputs