1 files changed, 86 insertions, 0 deletions
diff --git a/fpga/usrp2/sdr_lib/tx_frontend.v b/fpga/usrp2/sdr_lib/tx_frontend.v
new file mode 100644
index 000000000..d8525dd25
--- /dev/null
+++ b/fpga/usrp2/sdr_lib/tx_frontend.v
@@ -0,0 +1,86 @@
+
+module tx_frontend
+  #(parameter BASE=0,
+    parameter WIDTH_OUT=16)
+   (input clk, input rst,
+    input set_stb, input [7:0] set_addr, input [31:0] set_data,
+    input [23:0] tx_i, input [23:0] tx_q, input run,
+    output reg [WIDTH_OUT-1:0] dac_a, output reg [WIDTH_OUT-1:0] dac_b
+    );
+
+   // IQ balance --> DC offset --> rounding --> mux
+
+   wire [23:0] i_dco, q_dco, i_ofs, q_ofs;
+   wire [WIDTH_OUT-1:0] i_final, q_final;
+   wire [7:0]  mux_ctrl;
+   wire [35:0] corr_i, corr_q;
+   wire [23:0] i_bal, q_bal;
+   wire [17:0] mag_corr, phase_corr;
+   
+   setting_reg #(.my_addr(BASE+0), .width(24)) sr_0
+     (.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
+      .in(set_data),.out(i_dco),.changed());
+
+   setting_reg #(.my_addr(BASE+1), .width(24)) sr_1
+     (.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
+      .in(set_data),.out(q_dco),.changed());
+
+   setting_reg #(.my_addr(BASE+2),.width(18)) sr_2
+     (.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
+      .in(set_data),.out(mag_corr),.changed());
+   
+   setting_reg #(.my_addr(BASE+3),.width(18)) sr_3
+     (.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
+      .in(set_data),.out(phase_corr),.changed());
+  
+   setting_reg #(.my_addr(BASE+4), .width(8)) sr_4
+     (.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
+      .in(set_data),.out(mux_ctrl),.changed());
+
+   // IQ Balance
+   MULT18X18S mult_mag_corr
+     (.P(corr_i), .A(tx_i[23:6]), .B(mag_corr), .C(clk), .CE(1), .R(rst) ); 
+   
+   MULT18X18S mult_phase_corr
+     (.P(corr_q), .A(tx_i[23:6]), .B(phase_corr), .C(clk), .CE(1), .R(rst) );
+   
+   add2_and_clip_reg #(.WIDTH(24)) add_clip_i
+     (.clk(clk), .rst(rst), 
+      .in1(tx_i), .in2({{4{corr_i[35]}},corr_i[35:16]}), .strobe_in(1'b1), 
+      .sum(i_bal), .strobe_out());
+   
+   add2_and_clip_reg #(.WIDTH(24)) add_clip_q
+     (.clk(clk), .rst(rst), 
+      .in1(tx_q), .in2({{4{corr_q[35]}},corr_q[35:16]}), .strobe_in(1'b1),
+      .sum(q_bal), .strobe_out());
+
+   // DC Offset
+   add2_and_clip_reg #(.WIDTH(24)) add_dco_i
+     (.clk(clk), .rst(rst), .in1(i_dco), .in2(i_bal), .strobe_in(1'b1), .sum(i_ofs), .strobe_out());
+   
+   add2_and_clip_reg #(.WIDTH(24)) add_dco_q
+     (.clk(clk), .rst(rst), .in1(q_dco), .in2(q_bal), .strobe_in(1'b1), .sum(q_ofs), .strobe_out());
+
+   // Rounding
+   round_sd #(.WIDTH_IN(24),.WIDTH_OUT(WIDTH_OUT)) round_i
+     (.clk(clk), .reset(rst), .in(i_ofs),.strobe_in(1'b1), .out(i_final), .strobe_out());
+
+   round_sd #(.WIDTH_IN(24),.WIDTH_OUT(WIDTH_OUT)) round_q
+     (.clk(clk), .reset(rst), .in(q_ofs),.strobe_in(1'b1), .out(q_final), .strobe_out());
+
+   // Mux
+   always @(posedge clk)
+     case(mux_ctrl[3:0])
+       0 : dac_a <= i_final;
+       1 : dac_a <= q_final;
+       default : dac_a <= 0;
+     endcase // case (mux_ctrl[3:0])
+      
+   always @(posedge clk)
+     case(mux_ctrl[7:4])
+       0 : dac_b <= i_final;
+       1 : dac_b <= q_final;
+       default : dac_b <= 0;
+     endcase // case (mux_ctrl[7:4])
+      
+endmodule // tx_frontend