Abstarct: Heart disease is one of the leading causes of death throughout the world and also the most common cause of death in Iran. In order to diagnose heart disease, the first step is to know the state of your heart rate. To receive the Electrocardiogram, the amplifier requires design considerations, which include high mid-band gain, low noise, low power consumption, and small silicon area occupancy on the chip, so that signal can be amplified within the specified frequency range. For this purpose, the capacitive instrumentation amplifier is usually used. The total amount of capacitors for this structure, needs to be large in order to achieve the required gain. These occupy a large silicon area on the chip. The mid-band gain for this structure is obtained from the capacitors’ ratio. Therefore, if we calculate the mid-band gain of the amplifier in two stages instead of being constructed in one stage, the number of capacitors and occupied area on the chip will be reduced. Adding a stage to the circuit provides tunable gain and bandwidth concurrently. The proposed amplifier has three stages. The first stage is used as a low noise amplifier, second stage, as a tunable band pass filter and third stage is used for tunable and variable gain. In addition, to detect the QRS complex in the ECG signal, a latch comparator is placed at the proposed amplifier output. If a QRS signal is detected, a pulse is created at the comparator output. The proposed amplifier is implemented in a 0.18μm CMOS technology with a one-volt supply voltage and simulated by the Cadence virtuso tool. The post layout simulation results show that the amplifier has a tunable mid-band gain of 50.25 to 60.62 dB. Low cut-off frequency tuned from 394 mHz to 2.34 Hz. Also high cut-off frequency tuned from 135 Hz to 383 Hz. The simulated value of the input referred noise and Noise Efficiency Factor (NEF) of the amplifier are 1.53 μVrms and 1.23 respectively. The total power consumption is equal to 89.62 nW. The simulated value of the CMRR and PSRR of the amplifier are 75 dB and 53 dB respectively. Also the Total Harmonic Distortion (THD) has been measured about 2 percent.